1. Field of the Invention
The invention relates generally to devices for introducing additives, such as chemical or other liquid amendments, into a water supply line. More specifically, the invention pertains to a computerized apparatus and associated methods which are effective to inject an accurately metered flow of acid, fertilizers, or other liquid product into the incoming flow of a main water supply line used for agricultural or industrial purposes.
2. Description of the Prior Art
Devices providing metering of chemicals or other liquid product into a water supply line used for irrigation or in industry are well known in the prior art. The earliest metering systems simply introduced a chemical into a main water supply line at a fixed, predetermined rate, irrespective of the volume of water actually passing through the supply line. Later, more sophisticated proportionate chemical injection systems were developed. These systems were configured having a selected chemical-to-total flow ratio, effective to deliver chemical(s) into a supply line in proportion to the total flow measured in that line. Other prior art systems were designed to apply a predetermined weight of fertilizer in an aqueous solution, to a known acreage of land, over a particular period of time. Still other systems meter acid into a monitored incoming water supply line, to maintain a predetermined Ph in the outflowing water.
Such prior art chemical injection systems typically use a piston pump or a single diaphragm product pump to inject a chemical into the supply line. Diaphragm pumps are more desirable for chemical injection because the diaphragm separates the chemical solution from the other mechanical components of the pump. Owing to this physical isolation of the pumping mechanism from the chemical solution, diaphragm pumps can reliably pump abrasive and corrosive liquids, fertilizers, and acids.
Prior art systems vary the speed of the diaphragm pump to inject the appropriate amount of liquid product into the line. Because single diaphragm pumps have a large diaphragm running at a relatively slow stroke rate, such as 100 strokes per minute, they produce a pulsatile flow in the liquid delivered. As a consequence of this pulsing, accurate measurement of the precise rate of product flow is difficult, if not impossible. In addition, different chemicals or even the same chemical in different concentrations and temperatures will change the viscosity of the metered product. Different viscosities of the chemical product also significantly affect the accuracy of any product flow meter used for flow measurement.
Heretofore, such systems were calibrated for proper flow rate by using a calibration tube and a stop watch. Through a process of trial and error, the stroke length of the diaphragm pump is manually adjusted to draw a volume of the calibration tube at a single target delivery rate. This method is manual, tedious, time consuming, and not accurate over a range of product delivery rates. Nor does this method of calibration offer the features of constant monitoring and regulation of product flow rate during actual chemical injection. And, lacking the ability to make real time accurate measurements of both main line and product line flow rates, prior art devices lack the ability to log system performance and operation.
Consequently, room exists for improvement in the accuracy and ease with which prior art systems measure, deliver, and log the delivery of chemical amendments to an agricultural irrigation system, or an industrial water system.